Nitrogen gas makes up 78% of Earth’s atmosphere and is an essential component in amino acids and proteins.
However, plants and animals cannot use nitrogen gas directly.
Plants can only absorb nitrogen in the form of nitrates.
Nitrates and other minerals are taken into a plant via specially adapted root cells called root hair cells.
They are specially adapted by having a long extension that provides a large surface area for absorption.
Nitrates are absorbed by the process of active uptake/transport, which moves the mineral from an area of low concentration in the soil to an area of high concentration, against a concentration gradient, in the plant root.